Download Free Mississippi Kaskaskia St Louis Basin Becker Lake Dam No Name 250 Jefferson County Missouri Phase 1 Inspection Report National Dam Safety Program Book in PDF and EPUB Free Download. You can read online Mississippi Kaskaskia St Louis Basin Becker Lake Dam No Name 250 Jefferson County Missouri Phase 1 Inspection Report National Dam Safety Program and write the review.

This dam has been classified as unsafe, non-emergency by the St. Louis District as a result of the application of the following criteria: (a) Spillway will not pass 50 percent of the Probable Maximum Flood without overtopping the dam; (b) Overtopping of the dam could result in failure of the dam; and (c) Dam failure significantly increases the hazard to loss of life downstream.
Gudaitis Lake Dam is in the small size classification based on its maximum height of 25 ft and on its reservoir storage volume of about 180 ac-ft. The small dam classification includes dams between 25 and 40 ft in height or having storage capacities between 50 and 1000 ac-ft. The inspection and evaluation indicate the dam is in fair condition. This evaluation is primarily based on hydrologic analyses that indicate that a flood greater than 12 percent of the PMF will effectively overtop the dam. The dam will also be effectively overtopped by the one percent probability-of-occurrence (100 year) flood event. A 40 ft wide zone of slow seepage was noted at the toe of the dam, but the seepage water was not transporting any soil particles at the time of our inspection. The downstream face of the dam is heavily vegetated with relatively young trees up to 12 in. in diameter. This vegetation obscured portions of the dam from inspection. The spillway discharge channel is narrow and shallow and is bordered by many large trees. Deep gulley erosion is occurring where this channel traverses steeper slopes. Flood flows in this channel could cause overtopping of the channel and erosion of the channel walls, resulting in possible erosion at the toe of the dam.
Floyd Lake Dam has been classified by St Louis District, Corps of Engineers (SLD), as having a high hazard potential; we concur with this classification. The SLD estimated damage zone length extends approximately eight miles downstream of the dam. Within the potential downstream damage zone are 4 dwellings within the first mile and the town of Old Mines, approximately 2 mi downstream. The dam is classified small due to its 50 ac-ft storage capacity. The dam is 21 ft high. The classification for small size dams is based on a height between 25 and 40 ft of a storage capacity between 50 and 1000 ac-ft. The visual inspection and available information indicate the dam is in generally poor condition. The principal deficiencies noted were the inadequate spillway capacity, potential erosion at the toe of the dam by the flow in the discharge channel, and very dense vegetation on the downstream slope of the dam, obscuring the face from a thorough inspection. Seepage and stability analyses comparable to the requirements of the 'Recommended Guidelines for Safety Inspection of Dams' were not available, which is a deficiency that should be rectified. Hydraulic and hydrologic analyses indicate that the dam will be overtopped by the 10 percent probability-of-occurrence event (10-yr flood), and by a flood of greater than 5 percent of the PMF event. The PMF is defined as the flood event that may be expected to occur from the most severe combination of critical meteorological and hydrologic conditions that are reasonably possible in the region.
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